Sources and exposure risk of trace elements for traffic policemen in roadside locations

Samples of PM_2.5 and PM₁₀ at four types of roadside location (major road, secondary road, branch road, and expressway) in Tianjin were collected and analyzed in 2015. The average annual roadside PM_2.5 and PM₁₀ concentrations were higher than the national ambient air quality standard (NAAQS: GB3095-2012). The chromium (Cr), manganese (Mn), nickel (Ni), zinc (Zn), arsenic (As), and cadmium (Cd) concentrations in both PM_2.5 and PM₁₀ over four seasons displayed significant differences (p < 0.05). An enrichment factor (EF) analysis revealed that Cd, copper (Cu), Zn, As, Ni, and Pb in PM_2.5 and PM₁₀ mainly originated from anthropogenic sources. A factor analysis (FA) and correlation analysis (CA) revealed that vehicle emissions (exhaust and non-exhaust), soil dust, coal combustion, and industrial emissions were the main sources of roadside PM_2.5 and PM₁₀ in Tianjin. Both the total hazard quotients (total HQ) and the total carcinogenic risk (total CR) for selected elements in PM_2.5 and PM₁₀ were within acceptable limits. The HQ of Pb was higher than for other metals, and it should therefore be given special attention. The CR for traffic policemen was highest for Cr exposure (1.01 × 10⁻⁵ for PM_2.5 and 1.52 × 10⁻⁵ for PM₁₀), followed by As and Ni. A sensitivity analysis showed that the total contributions of the metal concentrations, exposure time (ET), and exposure frequency (EF) accounted for over 50% of the risk for Cr, As, and Ni, suggesting that these metals had the greatest impact on the uncertainty of health risk assessments.     

基于参数横摇的航行安全性研究

\t\t  目的  由于超大型集装箱船在波浪中稳性高的变化较为显著,对其参数横摇校核与安全评估要求较高,因此,\t\t  方法  基于参数横摇模式,针对在迎浪中航行的某10 000 TEU集装箱船,对其各个装载状况逐一并逐级进行计算。自主开发基于典型弱非线性三自由度模型的数值预报方法,对不满足第2层衡准要求的载况进行时域模拟,并综合考虑航速、波况的影响,全面探索其可能发生参数横摇的工况。\t\t  结果  根据衡准结果,得出相应的安全性评估与规避措施：降低重心高度、适当提高航速、尽量避免船舶横摇固有周期约等于2倍遭遇周期等均能有效避免参数横摇的发生。\t\t  结论  对10 000 TEU集装箱船进行的参数横摇全面校核评估能够更好地指导超大型集装箱船的总体设计,提高安全水平,具有较高的工程应用及参考价值。     

A stochastic optimization approach for the selection of reflective cracking mitigation techniques

PurposeIn Hot Mix Asphalt (HMA) overlays, the existing cracks in the underlying pavements can propagate upward to the new added overlay and may cause Reflective Cracks (RC). These cracks allow water infiltration to the underlying layers and causes further moisture damage as well as weakening the unbound layers. Over the years, several methods have been developed for mitigating the RCs. This study aims to investigate the current reflective cracking mitigation methods and develop a methodology for the selection of appropriate mitigation technique. The developed model is then applied to a case study in the state of Florida.MethodTo accomplish this goal, a nationwide literature review was conducted to better understand the current in practice methods in the United States. Moreover, a life cycle cost analysis (LCCA) in five different road types was performed to find the annuity of roadway rehabilitation for each of the mitigation methods. The uncertainty in the LCCA results is represented using Exploratory Modeling and Analysis (EMA) method. Then through a Multi Criteria Decision Making (MCDM) model, a stochastic optimization model was developed to find the appropriate reflective cracking mitigation solution under Florida’s climate and road conditions, based on different cost and performance weights.ResultsBased on the available data for the state of Florida, the LCCA results indicate that the annuity of maintaining the roadway with Fabrics and ISAC are lower compared to other methods. However, the results of stochastic optimization model reveal that while looking at the performance and cost at the same time, different methods would be more feasible. For instance, while the cost of the used method does not matter at all and only performance matters, STRATA® is more probable to be the appropriate mitigation technique. The findings of this research are critical for decision makers to better understand the most cost-effective mitigation technique in different conditions.     

公路基本建设项目设计阶段工程造价控制

公路工程造价控制,是工程项目管理的重要内容。文章分析了在公路基本建设项目设计阶段控制工程造价的重要性,阐述了设计阶段工程造价控制的必要条件,提出了对公路基本建设项目工程造价进行有效控制的措施。     

TEM技术在大牛地气田管道腐蚀评价中的应用

文中结合大牛地气田埋地管道腐蚀直接评价（ECDA,ICDA）实践,应用管道壁厚瞬变电磁（TEM）检测技术,通过在沿管道按一定间距布置测点进行基础检测,对所发现的管壁厚度异常点处再加密检测,从而确定腐蚀严重部位,较快地掌握气田整体管道质量情况,达到不需开挖、不破坏管道的良好检测效果。     

公路隧道环境影响评价中存在的问题与对策建议

公路隧道环境影响评价在预防和减缓隧道建设、运营对生态环境的影响上起着重要的作用.文章在对公路隧道环评实践过程中存在的现行法规难以完全满足环评需要、环评介入时间滞后以及其他一些环评技术问题进行分析讨论的基础上.提出了制定隧道环评专门法规、加强隧道环评监管和提高隧道环评人员素质的对策建议.     

基于PHA-LEC-SCL法公路隧道施工安全评价研究

为了制定科学的公路隧道施工安全评价的基本模式,针对公路隧道施工的危险、有害因素的危害程度及特殊工艺,将公路隧道施工系统分为隧道开挖、爆破、施工用电、施工通风、出碴与洞内运输、支护衬砌等6个主要子系统.运用预先危险性分析法(PHA)对公路隧道施工的危险、危害因素进行辨识和定性分析,结合作业条件危险性评价法(LEC)对公路隧道施工系统中各子系统进行危险性评价,定量分析计算PHA中的子系统各个危险因素的危险等级,并采用安全检查表(SCL)对公路隧道施工现场进行安全综合评价,建立了安全评价方法之间的内在联系.PHA-LEC-SCL法确立了公路隧道施工安全评价的基本模式.     

城市燃气管道第三方损坏的评价方法

第三方损坏评价是指对由于各种外力作用而使管道受损的可能性进行分级.根据影响第三方损坏因素的情况,采用故障树分析法和模糊综合评判法相结合的数学模型进行评价.通过故障树分析,得到引起第三方损坏的各种因素的重要度.再将之作为模糊综合评判法的权重向量,求得第三方损坏的综合评判向量,最后按照最大隶属度原则确定各管段第三方损坏可能性的等级.     

An integrated assessment of alternative land-based passenger transport policies: A case study in Tenerife

Over recent decades, there have been numerous cases of land-based transport policies that have lacked clear and coherent strategies. This has not only hampered the resolution of issues like road congestion, but has also created new ones (e.g. strong social opposition to new train infrastructures). The absence of such strategies highlights the need for long-term transport policies with a wider vision of the issues, since land-based transport cannot be considered from just a technical perspective.The main objective of this article is to implement a participatory integrated approach to facilitate the understanding of land-based passenger transport governance issues on Tenerife, in the Canary Islands. Relevant policy issues and alternatives are identified by the stakeholders involved. The inclusion of stakeholders in the assessment process is crucial to frame transport governance issues appropriately and to define and assess plausible policy alternatives. This assessment process even included a final step of validation of the results by stakeholders to foster discussion among them about transport issues and policy alternatives.Finally, due to the obstructive role played by some stakeholders in influencing past transport policies, an analysis of possible coalitions among stakeholders is also discussed.     

公路施工项目成本管理的探讨

对公路工程项目管理成本控制的原则进行分析。结合在滨德高速公路的施工项目,提出了成本控制措施。